This is a competing renewal of an R01 grant to study regulation of gamma-herpesvirus reactivation from latency. Gamma-herpesviruses are associated with the development of lymphoproliferative disorders and lymphoma, particularly in immunosuppressed individuals. A detailed understanding of how virus replication is triggered is critical to understanding the biology of gamma-herpesvirus infections, and may identify possible targets for interfering with viral persistence in the host. In this renewal application we propose to characterize reactivation from latency focusing on both EBV and murine gamma-herpesvirus 68 (.HV68). .HV68 infection of mice provides a tractable small animal model system for characterizing the role of specific genes to viral pathogenesis and maintenance of chronic infection. Aim 1. Regulation of EBV reactivation: 1a. Develop and characterize experimental systems for examining EBV reactivation. 1b. Determine the role of Zta and Rta autoactivation of Zp and Rp in virus reactivation. 1c. Determine the roles of individual cis-elements in regulating basal and induced levels of BRLF1and BZLF1 gene transcription. 1d. Determine the roles of specific cellular factors in regulating Zp and Rp activity. Aim 2. Regulation of gammaHV68 reactivation: 2a. Identify signaling pathways that trigger gammaHV68 reactivation. 2b. Identify and characterize cis-elements regulating gene 50 (Rta) expression. 2c. Characterize the roles of the gammaHV68 M1 protein and v-cyclin in reactivation. 2d. Identify other gammaHV68 genes involved in reactivation.